dev_server.py

from http.server import SimpleHTTPRequestHandler, ThreadingHTTPServer
from pathlib import Path


class SiteHandler(SimpleHTTPRequestHandler):
    def end_headers(self):
        self.send_header("Cache-Control", "no-store, no-cache, must-revalidate")
        self.send_header("Pragma", "no-cache")
        self.send_header("Expires", "0")
        super().end_headers()

    def send_error(self, code, message=None, explain=None):
        if code != 404:
            return super().send_error(code, message, explain)

        body = Path(__file__).with_name("404.html").read_bytes()
        self.send_response(404)
        self.send_header("Content-Type", "text/html; charset=utf-8")
        self.send_header("Content-Length", str(len(body)))
        self.end_headers()
        if self.command != "HEAD":
            self.wfile.write(body)


if __name__ == "__main__":
    print("Serving on http://localhost:8000")
    ThreadingHTTPServer(("", 8000), SiteHandler).serve_forever()